TY - JOUR A1 - Recknagel, Sebastian A1 - Koch, Matthias A1 - Wise, S. A. A1 - Panne, Ulrich T1 - Fifteenth international symposium on biological and environmental reference materials (BERM-15) N2 - The 15th International Symposium on Biological and Environmental Reference Materials (BERM-15), organized by BAM, took place at in Berlin in September 2018. An overview on main topics of the conference is given. KW - BERM KW - Reference materials PY - 2019 DO - https://doi.org/10.1007/s00769-019-01377-9 SN - 1432-0517 SN - 0949-1775 VL - 24 IS - 3 SP - 249 EP - 250 PB - Springer Verlag AN - OPUS4-48203 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kotthoff, Lisa A1 - Schwerdtle, T. A1 - Koch, Matthias T1 - Electrochemistry coupled to LC/HRMS to investigate transformation products of the veterinary drug monensin N2 - The knowledge of transformation pathways and identification of transformation products (TPs) of veterinary drugs is important for health, food and environmental matters. Monensin (MON) is an ionophore antibiotic widely used to cure and prevent coccidiosis by chicken especially in broiler farming. Residues can be found in food products (chicken and eggs) and in the environment (manure, soil, water). Several transformation processes can alter the parent compound MON, ranging from biotransformation in living organism to biotic/abiotic and microbial processes in environmental matters. The main objective of this work was to investigate the potential of electrochemistry (EC) to simulate oxidative transformation processes of MON and to predict TPs. An electrochemical reactor was used consisting of a flow-through cell with a glassy carbon working electrode. Derived TPs were analyzed by online coupling of EC and high-resolution mass spectrometry (HRMS) and LC/HRMS offline measurements. Among the generated TPs already known as well as unknown TPs of MON could be found. Additionally, MON was subjected also to other transformation experiments like metabolism tests with rat microsomes or the pH-dependent hydrolysis. As a result, different targeted and suspected TPs could be identified by analysis with LC/HRMS. An overview of detected/identified TPs from this study will be presented in comparison to literature known metabolites and TPs. T2 - ElCheMS 2019 – 5th Workshop on Electrochemistry/Mass Spectrometry 2019 CY - Münster, Germany DA - 11.06.2019 KW - Transformation product KW - Electrochemistry KW - High-resolution MS KW - Ionophore antibiotic PY - 2019 AN - OPUS4-48209 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Geilert, Sonja A1 - Vogl, Jochen A1 - Rosner, M. A1 - Eichert, T. T1 - Boron isotope variability related to boron speciation (change during uptake and transport) in bell pepper plants and SI traceable n(11B)/n(10B) ratios for plant reference materials N2 - Rationale: Boron (B) is an essential micronutrient in plants and its isotope variations are used to gain insights into plant metabolism, which is important for crop plant cultivation. B isotope variations were used to trace intra‐plant fractionation mechanisms in response to the B concentration in the irrigation water spanning the range from B depletion to toxic levels. Methods: A fully validated analytical procedure based on multi‐collector inductively coupled plasma mass spectrometry (MC‐ICP‐MS), sample decomposition and B Matrix separation was applied to study B isotope fractionation. The Validation was accomplished by establishing a complete uncertainty budget and by applying reference materials, yielding expanded measurement uncertainties of 0.8‰ for pure boric acid solutions and ≤1.5‰ for processed samples. With this validated procedure SI traceable B isotope amount ratios were determined in plant reference materials for the first time. Results: The B isotope compositions of Irrigation water and bell pepper samples suggest passive diffusion of the heavy 11B isotope into the roots during low to high B concentrations while uptake of the light 10B isotope was promoted during B depletion, probably by active processes. A systematic enrichment of the heavy 11B isotope in higher located plant parts was observed (average Δ11Bleaf‐roots = 20.3 ± 2.8‰ (1 SD)), possibly by a facilitated transport of the heavy 11B isotope to growing Meristems by B transporters. Conclusions: The B isotopes can be used to identify plant metabolism in Response to the B concentration in the irrigation water and during intra‐plant B transfer. The large B isotope fractionation within the plants demonstrates the importance of biological B cycling for the global B cycle. KW - isotope fractionation KW - boron KW - delta value KW - metabolism KW - bell pepper KW - SI traceability KW - measurement uncertainty PY - 2019 DO - https://doi.org/10.1002/rcm.8455 SN - 1097-0231 SN - 0951-4198 VL - 33 IS - 13 SP - 1137 EP - 1147 PB - John Wiley & Sons Ltd. AN - OPUS4-48213 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Haferkamp, Sebastian A1 - Paul, Andrea A1 - Michalchuk, Adam A1 - Emmerling, Franziska T1 - Unexpected polymorphism during a catalyzed mechanochemical Knoevenagel condensation N2 - The transformation of a base-catalyzed, mechano-assisted Knoevenagel condensation of mono-fluorinated benzaldehyde derivatives (p-, m-, o-benzaldehyde) with malonodinitrile was investigated in situ and in real time. Upon milling, the para-substituted product was found to crystallize initially into two different polymorphic forms, depending on the quantity of catalyst used. For low catalyst concentrations, a mechanically metastable phase (monoclinic) was initially formed, converting to the mechanically stable phase (triclinic) upon further grinding. Instead, higher catalyst concentrations crystallize directly as the triclinic product. Inclusion of catalyst in the final product, as evidenced by mass spectrometric analysis, suggests this complex polymorphic pathway may be due to seeding effects. Multivariate analysis for the in situ Raman spectra supports this complex formation pathway, and offers a new approach to monitoring multi-phase reactions during ball milling. KW - Ball milling KW - C-C coupling KW - In situ KW - Mechanochemistry KW - Multivariate data analysis PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-481872 DO - https://doi.org/10.3762/bjoc.15.110 SN - 1860-5397 VL - 15 SP - 1141 EP - 1148 PB - Beilstein Insitut CY - Frankfurt am Main AN - OPUS4-48187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. T1 - Laser induced Plasma: Modeling and diagnostics N2 - Laser-induced plasmas are widely used in many areas of science and technology; examples include spectrochemical analysis, thin film deposition, material processing, and even jet propulsion. Several topics will be addressed. First, general phenomenology of laser-induced plasmas will be discussed. Then, a chemical model will be presented based on a coupled solution of Navier-Stokes, state, radiative transfer, material transport, and chemical (Guldberg-Waage) equations. Results of computer simulations for several chemical systems will be shown and compared to experimental observations obtained by optical imaging, spectroscopy, and tomography. The latter diagnostic tools will also be briefly discussed. T2 - Lecture at the Dept of Chemistry of Czeged University (Hungary) on 31.05.2019 CY - Czeged, Hungary DA - 31.05.2019 KW - Plasma KW - LIBS KW - Plasma modeling PY - 2019 AN - OPUS4-48188 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. T1 - Several approaches to calibration-free LIBS: Advantages and pitfalls N2 - An overview of calibration-free laser induced breakdown spectroscopy (CF LIBS) methods is presented. Advantages and pitfalls of these methods are critically discussed. T2 - Workshop of the Spectrochemical Working Committee (SWC) of the Hungarian Academy of Sciences CY - Budapest, Hungary DA - 05.06.2019 KW - Calibration-free LIBS KW - CF LIBS algorithms PY - 2019 AN - OPUS4-48189 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Weigert, Florian A1 - Frenzel, Florian A1 - Würth, Christian A1 - Hoffmann, Katrin A1 - Martynenko, Iris A1 - Dhamo, Lorena T1 - Optical properties of different types of luminescent nanocrystals at the ensemble and single emitter level N2 - Applications of luminescent nanomaterials like semiconductor nanocrystals (QDs) and lanthanide-based upconversion nanocrystals (UCNPs) in the life sciences such as bioimaging studies or their use as reporter in assays call for a correlation of the photoluminescence (PL) properties of these nanomaterials on ensemble and single particle levels. This is particularly relevant within the context of continuously decreasing detection limits. Aiming at optimum nanomaterials for spectroscopic and microscopic applications, we examine the optical properties of QDs like II/VI QDs and cadmium-free AgInS2/ZnS QDs (AIS/ZnS) and UCNPs of different chemical composition, size, and particle architecture for ensembles and single particles. This includes PL spectra, PL quantum yields (ΦF), brightness values, blinking behavior, and PL decay kinetics. For UCNPs with their nonlinear spectrally converted PL excited by sequential multiphoton absorption, these measurements were also done as a function of excitation power density (P). Special emphasis is dedicated to the performance parameters ΦF and brightness, that determine signal size and provide a measure for nanocrystal quality.[1-5] Systematic studies of the excitation energy dependence (EED) [6] of the PL properties of II/VI and ternary AgInS2/ZnS QDs reveal the potential of this relatively simple method for providing insights into the electronic energy structure of QDs. The intrinsic nature of the inhomogeneous broadening of the PL bands of AIS/ZnS QDs was confirmed by single particle spectroscopy.[5] By combining P-dependent integration spectroscopy and single particle measurements of UCNPs, using a new custom-made setup, consisting of different lasers, an inverted microscope, different detectors, and an AFM, we could study the P-dependent optical properties of these nonlinear emitters from ~10 W/cm2 up to ~105 W/cm2. These results provide optimum dopant ion concentrations for bioanalytical, spectroscopic, and microscopic applications of UCNP. Acknowledgement. Financial support by grants RE1203/12-3 and RE1203/20-1 (support of F. Weigert, L. Dhamo, and F. Frenzel) from German Research Council (DFG) is acknowledged. T2 - 17th Internatinal Congress on Photobiology CY - Barcelona, Spain DA - 25.08.2019 KW - Nanoparticle KW - Quantum dot KW - Fluorescence KW - Single particle spectroscopy KW - Mechanism KW - Lifetime KW - Exciton KW - Ternary quantum dot KW - AIS QD KW - Synthesis KW - Shell KW - Surface chemistry PY - 2019 AN - OPUS4-48877 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute ED - Kaiser, Martin ED - Würth, Christian ED - Kraft, Marco ED - Soukka, T. T1 - Explaining the influence of dopant concentration and excitation power density on the luminescence and brightness of β-NaYF4:Yb3+,Er3+ nanoparticles: Measurements and simulations N2 - We assessed the influence of Yb3+ and Er3+ dopant concentration on the relative spectral distribution, quantum yield (  UC), and decay kinetics of the upconversion luminescence (UCL) and particle brightness (BUC) for similarly sized (33 nm) oleate-capped -NaYF4:Yb3+,Er3+ upconversion (UC) nanoparticles (UCNPs) in toluene at broadly varied excitation power densities (P). This included an Yb3+ series where the Yb3+ concentration was varied between 11%–21% for a constant Er3+ concentration of 3%, and an Er3+ series, where the Er3+ concentration was varied between 1%–4% for a constant Yb3+ concentration of 14%. The results were fitted with a coupled rate equation model utilizing the UCL data and decay kinetics of the green and red Er3+ emission and the Yb3+ luminescence at 980 nm. An increasing Yb3+ concentration favors a pronounced triphotonic population of 4F9/2 at high P by an enhanced back energy transfer (BET) from the 4G11/2 level. Simultaneously, the Yb3+-controlled UCNPs absorption cross section overcompensates for the reduction in  UC with increasing Yb3+ concentration at high P, resulting in an increase in BUC. Additionally, our results show that an increase in Yb3+ and a decrease in Er3+ concentration enhance the color tuning range by P. These findings will pave the road to a deeper understanding of the energy transfer processes and their contribution to efficient UCL, as well as still debated trends in green-to-red intensity ratios of UCNPs at different P. KW - Nanoparticle KW - Lanthanide KW - Upconversion nanoparticle KW - Fluorescence KW - Integration sphere spectroscopy KW - Mechanism KW - Lifetime, synthesis KW - Surface chemistry KW - Yb(III) KW - Er(III) KW - Energy transfer KW - Absolute measurement KW - Quantum yield PY - 2019 DO - https://doi.org/10.1007/s12274-019-2450-4 SN - 1998-0124 SN - 1998-0000 VL - 12 IS - 8 SP - 1871 EP - 1879 PB - Springer AN - OPUS4-48880 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Faßbender, Sebastian A1 - Döring, A.-K. A1 - Meermann, Björn T1 - Development of complementary CE-MS methods for speciation analysis of pyrithione-based antifouling agents N2 - In the recent decade, metal pyrithione complexes have become important biocides for antifouling purposes in shipping. The analysis of metal pyrithione complexes and their degradation products/species in environmental samples is challenging because they exhibit fast UV degradation, transmetalation, and ligand substitution and are known to be prone to spontaneous species transformation within a chromatographic system. The environmental properties of the pyrithione species, e.g., toxicity to target and non-target organisms, are differing strongly, and it is therefore inevitable to identify as well as quantify all species separately. To cope with the separation of metal pyrithione species with minimum species transformation during analysis, a capillary electrophoresis (CE)–based method was developed. The hyphenation of CE with selective electrospray ionization- and inductively coupled plasma–mass spectrometry (ESI-, ICP-MS) provided complementary molecular and elemental information for the identification and quantification of pyrithione species. To study speciation of pyrithiones, a leaching experiment of several commercial antifouling paints containing zinc pyrithione in ultrapure and river water was conducted. Only the two species pyrithione (HPT) and dipyrithione ((PT)2) were found in the leaching media, in concentrations between 0.086 and 2.4 μM (HPT) and between 0.062 and 0.59 μM ((PT)2), depending on the paint and leaching medium. The limits of detection were 20 nM (HPT) and 10 nM ((PT)2). The results show that complementary CE-MS is a suitable tool for mechanistical studies concerning species transformation (e.g., degradation) and the identification of target species of metal pyrithione complexes in real surface water matrices, laying the ground for future environmental studies. KW - Complementary MS KW - Environmental speciation KW - Capillary electrophoresis-mass spectrometry KW - Antifouling biocides PY - 2019 DO - https://doi.org/10.1007/s00216-019-02094-5 SN - 1618-2642 VL - 411 IS - 27 SP - 7261 EP - 7272 PB - Springer CY - Berlin, Heidelberg AN - OPUS4-48962 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Özelci, Ersan A1 - Rühle, Bastian A1 - Weigert, Florian A1 - Lubotzky, B. A1 - Kewes, G. A1 - Resch-Genger, Ute A1 - Benson, O. T1 - Quantitative measurements of the pH-sensitive quantum yield of fluorophores in mesoporous silica thin films using a drexhage-type experiment N2 - The photoluminescence quantum yield characterizes the performance of emitters for applications in optical devices, as reporters or probes in material and analytical sciences, and for sensing applications. Quantum yield measurements are challenging for luminescent molecules and nanocrystals immobilized in thin films for many sensor applications, particularly if spatially resolved quantitative luminescence information is desired. We show here that a Drexhage-type experiment, where a silver-coated millimeter-sized sphere is used to modify the local density of states, can provide an elegant approach to counter this challenge. As a representative example of the potential of this method, we measure the pH-dependent photoluminescence quantum yield of fluorescein isothiocyanate bound to a thin mesoporous silica film. The results were compared with those of the studies on the pH dependence of the same dye in solution. We found that our approach can link single fluorophore studies to ensemble measurements and pave the way for the spatially resolved fluorescence measurements of ultralow concentrations of emitters utilized as optically active elements and reporters in thin sensor films or incorporated into membranes. KW - Fluorescence KW - Quantum yield KW - Method KW - pH KW - Dye KW - Sensor KW - Fluorescein KW - Film KW - Silica KW - Single molecule KW - Lifetime KW - Absolute quantum yield PY - 2019 DO - https://doi.org/10.1021/acs.jpcc.9b03917 SN - 1932-7447 SN - 1932-7455 VL - 123 IS - 33 SP - 20468 EP - 20475 PB - ACS Publications AN - OPUS4-48984 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -